The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, it should not be assumed that any of the approaches described in this section qualify as prior art merely by virtue of their inclusion in this section.
The increase in the use of displays in various electronic components has increased the pressure on display manufacturers to provide components that provide better performance. The performance parameters include readability, power consumption, resolution, cost, and sunlight readability. Display manufacturers employ various techniques to improve performance based on these parameters. In the field of liquid crystal displays, there exists a need for a technique that produces a high resolution in LCDs that are roomlight readable with the backlight off, and sunlight readable. Additionally, a need exists to develop an LCD that shows a high resolution in black, white and shades of grey.
Conventional backlit LCDs comprise a light source, such as one or more light-emitting diodes and a light guide. Light rays emitted by the light source are directed in all directions, but liquid crystal materials require light aligned in a single direction if the liquid crystal material is to function as a light valve. Therefore, a linear polarizer is layered over the light source and functions to polarize or align light waves of the light source in a single plane. The polarized light then passes through pixels, color filters, other films, and a second polarizer to produce a visible display image.
Unfortunately, conventional polarizers function by absorbing a large amount of the light waves that are not directed in the plane of polarization. Consequently, polarizers cause loss of a substantial amount of light intensity. Loss of 50% or more of the light produced by the light source is not unusual. A result is that to produce a display with acceptable brightness, the light source must be constructed with sufficient brightness to overcome the loss experienced at the first polarizer. Power consumption is directly related to brightness, and therefore a portion of the power consumed in a conventional LCD is ultimately wasted in the form of light loss in the polarizer.
Further, LCDs with polarizers suffer from reduced or limited reflectance and readability, as the polarizers cause the LCD to appear dim. For example, the second polarizer may absorb as much as 45% of incident or ambient light rays cast upon the LCD, and may absorb as much as 90% of the same rays upon reflection from reflective elements of the LCD. Therefore, in practice it is not possible for an LCD that uses polarizers to mimic closely the appearance of text on paper or to achieve performance similar to e-paper displays.